Thanks. I figured out part of that today by studying the manual. I removed the lid, and doused the whole thing with spray carb cleaner, and then used a little Permatex to seal the lid as the old gasket was shot. I'm thinking it might be a good idea to replace the hoses going to and from the crab, even thouygh they look okay.
Still won't start without thumb choking the carb- I suspect the missing airbox may be a factor here. Not enough resistance. I'm looking at a couple of airboxes on eBay right now but I may go with something homemade.